commit a66b40197ffea632c18941b690e98de5dc74f80c
author Venkatesh Srinivas <venkateshs@fuchsia.infra.roller.chromium.org> Tue Nov 22 04:36:53 2022 +0000
committer Copybara-Service <copybara-worker@google.com> Mon Nov 21 20:37:41 2022 -0800
tree f38711b5530322901208ed3c3a93591206a4c4dc
parent 766cddadd8987efdaa2c50597169eaa9c363d03b

[roll] Roll fuchsia [kernel][x86] Spectre V2/RETBLEED: Don't enable STIBP if SMT isn't present

STIBP is 'single-thread indirect branch predictor' mode, a mode that
prevents code running on one hyperthread from influencing branch
predictions on its paired hyperthread. On some processors, fully
mitigating Spectre V2 or RETBLEED requires STIBP to be set. STIBP is not
required if hyperthreading/SMT isn't present or enabled.

Don't bother enabling STIBP for Spectre V2 or RETBLEED mitigations if
hyperthreading is not present or enabled; this avoids unnecessary
performance impacts from STIBP.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/747663
Original-Revision: a796173a572228cac35e773592d43ced21ce6682
GitOrigin-RevId: f23fa6479133906aca7e35ff83c8958ff2b80be1
Change-Id: Ie1358eedf200e818f937b03c288d0bf0531c3c77

stem

diff --git a/stem b/stem
index a24417d..41ce8c8 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
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+             revision="a796173a572228cac35e773592d43ced21ce6682"/>
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